Search Results

You are looking at 91 - 100 of 116 items for

  • Author or Editor: William E. Johns x
  • Refine by Access: All Content x
Clear All Modify Search
David R. Smith
,
William A. Krayer
,
Kathryn M. Ginger
,
Michael A. Rosenthal
,
Jo Ann P. Mulvany
,
Walter Sanford
,
Juanita J. Matkins
,
Loisteen E. Harrell
,
Bonnie Smith
,
G. Jayne Koester
,
Richard L. Lees
,
John D. Moore
, and
Frankie C. Vann

Project ATMOSPHERE Atmospheric Education Resource Agents (AERAs) from the mid-Atlantic states conducted their second annual regional workshop for teachers. The focus of this conference was hazardous weather. Over 150 educators from 10 states and the District of Columbia attended this one-day event held in Silver Spring, Maryland. The workshop included presentations by meteorologists and scientists from the National Oceanic and Atmospheric Administration, the Environmental Protection Agency, private corporations, and universities as well as by the AERAs themselves. The presentations were designed to develop basic understandings about hazardous weather and to provide guidance about how to deal with its effects. The orientation of the program was hands on, including a number of activities for teachers to implement in the classroom. This conference demonstrates how educators and scientists can form partnerships to improve science education.

Full access
David P. Rogers
,
Clive E. Dorman
,
Kathleen A. Edwards
,
Ian M. Brooks
,
W. Kendall Melville
,
Stephen D. Burk
,
William T. Thompson
,
Teddy Holt
,
Linda M. Ström
,
Michael Tjernström
,
Branko Grisogono
,
John M. Bane
,
Wendell A. Nuss
,
Bruce M. Morley
, and
Allen J. Schanot

Some of the highlights of an experiment designed to study coastal atmospheric phenomena along the California coast (Coastal Waves 1996 experiment) are described. This study was designed to address several problems, including the cross-shore variability and turbulent structure of the marine boundary layer, the influence of the coast on the development of the marine layer and clouds, the ageostrophy of the flow, the dynamics of trapped events, the parameterization of surface fluxes, and the supercriticality of the marine layer.

Based in Monterey, California, the National Center for Atmospheric Research (NCAR) C-130 Hercules and the University of North Carolina Piper Seneca obtained a comprehensive set of measurements on the structure of the marine layer. The study focused on the effects of prominent topographic features on the wind. Downstream of capes and points, narrow bands of high winds are frequently encountered. The NCAR-designed Scanning Aerosol Backscatter Lidar (SABL) provided a unique opportunity to connect changes in the depth of the boundary layer with specific features in the dynamics of the flow field.

An integral part of the experiment was the use of numerical models as forecast and diagnostic tools. The Naval Research Laboratory's Coupled Ocean Atmosphere Model System (COAMPS) provided high-resolution forecasts of the wind field in the vicinity of capes and points, which aided the deployment of the aircraft. Subsequently, this model and the MIUU (University of Uppsala) numerical model were used to support the analysis of the field data.

These are some of the most comprehensive measurements of the topographically forced marine layer that have been collected. SABL proved to be an exceptionally useful tool to resolve the small-scale structure of the boundary layer and, combined with in situ turbulence measurements, provides new insight into the structure of the marine atmosphere. Measurements were made sufficiently far offshore to distinguish between the coastal and open ocean effects. COAMPS proved to be an excellent forecast tool and both it and the MIUU model are integral parts of the ongoing analysis. The results highlight the large spatial variability that occurs directly in response to topographic effects. Routine measurements are insufficient to resolve this variability. Numerical weather prediction model boundary conditions cannot properly define the forecast system and often underestimate the wind speed and surface wave conditions in the nearshore region.

This study was a collaborative effort between the National Science Foundation, the Office of Naval Research, the Naval Research Laboratory, and the National Oceanographic and Atmospheric Administration.

Full access
Christopher J. Anderson
,
Raymond W. Arritt
,
Zaitao Pan
,
Eugene S. Takle
,
William J. Gutowski Jr.
,
Francis O. Otieno
,
Renato da Silva
,
Daniel Caya
,
Jens H. Christensen
,
Daniel Lüthi
,
Miguel A. Gaertner
,
Clemente Gallardo
,
Filippo Giorgi
,
René Laprise
,
Song-You Hong
,
Colin Jones
,
H-M. H. Juang
,
J. J. Katzfey
,
John L. McGregor
,
William M. Lapenta
,
Jay W. Larson
,
John A. Taylor
,
Glen E. Liston
,
Roger A. Pielke Sr.
, and
John O. Roads

Abstract

Thirteen regional climate model (RCM) simulations of June–July 1993 were compared with each other and observations. Water vapor conservation and precipitation characteristics in each RCM were examined for a 10° × 10° subregion of the upper Mississippi River basin, containing the region of maximum 60-day accumulated precipitation in all RCMs and station reports.

All RCMs produced positive precipitation minus evapotranspiration (PE > 0), though most RCMs produced PE below the observed range. RCM recycling ratios were within the range estimated from observations. No evidence of common errors of E was found. In contrast, common dry bias of P was found in the simulations.

Daily cycles of terms in the water vapor conservation equation were qualitatively similar in most RCMs. Nocturnal maximums of P and C (convergence) occurred in 9 of 13 RCMs, consistent with observations. Three of the four driest simulations failed to couple P and C overnight, producing afternoon maximum P. Further, dry simulations tended to produce a larger fraction of their 60-day accumulated precipitation from low 3-h totals.

In station reports, accumulation from high (low) 3-h totals had a nocturnal (early morning) maximum. This time lag occurred, in part, because many mesoscale convective systems had reached peak intensity overnight and had declined in intensity by early morning. None of the RCMs contained such a time lag. It is recommended that short-period experiments be performed to examine the ability of RCMs to simulate mesoscale convective systems prior to generating long-period simulations for hydroclimatology.

Full access
Ariel E. Cohen
,
Richard L. Thompson
,
Steven M. Cavallo
,
Roger Edwards
,
Steven J. Weiss
,
John A. Hart
,
Israel L. Jirak
,
William F. Bunting
,
Jaret W. Rogers
,
Steven F. Piltz
,
Alan E. Gerard
,
Andrew D. Moore
,
Daniel J. Cornish
,
Alexander C. Boothe
, and
Joel B. Cohen

Abstract

During the 2014–15 academic year, the National Oceanic and Atmospheric Administration (NOAA) National Weather Service Storm Prediction Center (SPC) and the University of Oklahoma (OU) School of Meteorology jointly created the first SPC-led course at OU focused on connecting traditional theory taught in the academic curriculum with operational meteorology. This class, “Applications of Meteorological Theory to Severe-Thunderstorm Forecasting,” began in 2015. From 2015 through 2017, this spring–semester course has engaged 56 students in theoretical skills and related hands-on weather analysis and forecasting applications, taught by over a dozen meteorologists from the SPC, the NOAA National Severe Storms Laboratory, and the NOAA National Weather Service Forecast Offices. Following introductory material, which addresses many theoretical principles relevant to operational meteorology, numerous presentations and hands-on activities focused on instructors’ areas of expertise are provided to students. Topics include the following: storm-induced perturbation pressure gradients and their enhancement to supercells, tornadogenesis, tropical cyclone tornadoes, severe wind forecasting, surface and upper-air analyses and their interpretation, and forecast decision-making. This collaborative approach has strengthened bonds between meteorologists in operations, research, and academia, while introducing OU meteorology students to the vast array of severe thunderstorm forecast challenges, state-of-the-art operational and research tools, communication of high-impact weather information, and teamwork skills. The methods of collaborative instruction and experiential education have been found to strengthen both operational–academic relationships and students’ appreciation of the intricacies of severe thunderstorm forecasting, as detailed in this article.

Full access
David J. Diner
,
Thomas P. Ackerman
,
Theodore L. Anderson
,
Jens Bösenberg
,
Amy J. Braverman
,
Robert J. Charlson
,
William D. Collins
,
Roger Davies
,
Brent N. Holben
,
Chris A . Hostetler
,
Ralph A. Kahn
,
John V. Martonchik
,
Robert T. Menzies
,
Mark A. Miller
,
John A. Ogren
,
Joyce E. Penner
,
Philip J. Rasch
,
Stephen E. Schwartz
,
John H. Seinfeld
,
Graeme L. Stephens
,
Omar Torres
,
Larry D. Travis
,
Bruce A . Wielicki
, and
Bin Yu

Aerosols exert myriad influences on the earth's environment and climate, and on human health. The complexity of aerosol-related processes requires that information gathered to improve our understanding of climate change must originate from multiple sources, and that effective strategies for data integration need to be established. While a vast array of observed and modeled data are becoming available, the aerosol research community currently lacks the necessary tools and infrastructure to reap maximum scientific benefit from these data. Spatial and temporal sampling differences among a diverse set of sensors, nonuniform data qualities, aerosol mesoscale variabilities, and difficulties in separating cloud effects are some of the challenges that need to be addressed. Maximizing the longterm benefit from these data also requires maintaining consistently well-understood accuracies as measurement approaches evolve and improve. Achieving a comprehensive understanding of how aerosol physical, chemical, and radiative processes impact the earth system can be achieved only through a multidisciplinary, interagency, and international initiative capable of dealing with these issues. A systematic approach, capitalizing on modern measurement and modeling techniques, geospatial statistics methodologies, and high-performance information technologies, can provide the necessary machinery to support this objective. We outline a framework for integrating and interpreting observations and models, and establishing an accurate, consistent, and cohesive long-term record, following a strategy whereby information and tools of progressively greater sophistication are incorporated as problems of increasing complexity are tackled. This concept is named the Progressive Aerosol Retrieval and Assimilation Global Observing Network (PARAGON). To encompass the breadth of the effort required, we present a set of recommendations dealing with data interoperability; measurement and model integration; multisensor synergy; data summarization and mining; model evaluation; calibration and validation; augmentation of surface and in situ measurements; advances in passive and active remote sensing; and design of satellite missions. Without an initiative of this nature, the scientific and policy communities will continue to struggle with understanding the quantitative impact of complex aerosol processes on regional and global climate change and air quality.

Full access
Gregory C. Johnson
,
Rick Lumpkin
,
Tim Boyer
,
Francis Bringas
,
Ivona Cetinić
,
Don P. Chambers
,
Lijing Cheng
,
Shenfu Dong
,
Richard A. Feely
,
Baylor Fox-Kemper
,
Eleanor Frajka-Williams
,
Bryan A. Franz
,
Yao Fu
,
Meng Gao
,
Jay Garg
,
John Gilson
,
Gustavo Goni
,
Benjamin D. Hamlington
,
Helene T. Hewitt
,
William R. Hobbs
,
Zeng-Zhen Hu
,
Boyin Huang
,
Svetlana Jevrejeva
,
William E. Johns
,
Sato Katsunari
,
John J. Kennedy
,
Marion Kersalé
,
Rachel E. Killick
,
Eric Leuliette
,
Ricardo Locarnini
,
M. Susan Lozier
,
John M. Lyman
,
Mark A. Merrifield
,
Alexey Mishonov
,
Gary T. Mitchum
,
Ben I. Moat
,
R. Steven Nerem
,
Dirk Notz
,
Renellys C. Perez
,
Sarah G. Purkey
,
Darren Rayner
,
James Reagan
,
Claudia Schmid
,
David A. Siegel
,
David A. Smeed
,
Paul W. Stackhouse
,
William Sweet
,
Philip R. Thompson
,
Denis L. Volkov
,
Rik Wanninkhof
,
Robert A. Weller
,
Caihong Wen
,
Toby K. Westberry
,
Matthew J. Widlansky
,
Josh K. Willis
,
Lisan Yu
, and
Huai-Min Zhang
Free access
John T. Sullivan
,
Timothy Berkoff
,
Guillaume Gronoff
,
Travis Knepp
,
Margaret Pippin
,
Danette Allen
,
Laurence Twigg
,
Robert Swap
,
Maria Tzortziou
,
Anne M. Thompson
,
Ryan M. Stauffer
,
Glenn M. Wolfe
,
James Flynn
,
Sally E. Pusede
,
Laura M. Judd
,
William Moore
,
Barry D. Baker
,
Jay Al-Saadi
, and
Thomas J. McGee

Abstract

Coastal regions have historically represented a significant challenge for air quality investigations because of water–land boundary transition characteristics and a paucity of measurements available over water. Prior studies have identified the formation of high levels of ozone over water bodies, such as the Chesapeake Bay, that can potentially recirculate back over land to significantly impact populated areas. Earth-observing satellites and forecast models face challenges in capturing the coastal transition zone where small-scale meteorological dynamics are complex and large changes in pollutants can occur on very short spatial and temporal scales. An observation strategy is presented to synchronously measure pollutants “over land” and “over water” to provide a more complete picture of chemical gradients across coastal boundaries for both the needs of state and local environmental management and new remote sensing platforms. Intensive vertical profile information from ozone lidar systems and ozonesondes, obtained at two main sites, one over land and the other over water, are complemented by remote sensing and in situ observations of air quality from ground-based, airborne (both personned and unpersonned), and shipborne platforms. These observations, coupled with reliable chemical transport simulations, such as the National Oceanic and Atmospheric Administration (NOAA) National Air Quality Forecast Capability (NAQFC), are expected to lead to a more fully characterized and complete land–water interaction observing system that can be used to assess future geostationary air quality instruments, such as the National Aeronautics and Space Administration (NASA) Tropospheric Emissions: Monitoring of Pollution (TEMPO), and current low-Earth-orbiting satellites, such as the European Space Agency’s Sentinel-5 Precursor (S5-P) with its Tropospheric Monitoring Instrument (TROPOMI).

Open access
Stanley G. Benjamin
,
Stephen S. Weygandt
,
John M. Brown
,
Ming Hu
,
Curtis R. Alexander
,
Tatiana G. Smirnova
,
Joseph B. Olson
,
Eric P. James
,
David C. Dowell
,
Georg A. Grell
,
Haidao Lin
,
Steven E. Peckham
,
Tracy Lorraine Smith
,
William R. Moninger
,
Jaymes S. Kenyon
, and
Geoffrey S. Manikin

Abstract

The Rapid Refresh (RAP), an hourly updated assimilation and model forecast system, replaced the Rapid Update Cycle (RUC) as an operational regional analysis and forecast system among the suite of models at the NOAA/National Centers for Environmental Prediction (NCEP) in 2012. The need for an effective hourly updated assimilation and modeling system for the United States for situational awareness and related decision-making has continued to increase for various applications including aviation (and transportation in general), severe weather, and energy. The RAP is distinct from the previous RUC in three primary aspects: a larger geographical domain (covering North America), use of the community-based Advanced Research version of the Weather Research and Forecasting (WRF) Model (ARW) replacing the RUC forecast model, and use of the Gridpoint Statistical Interpolation analysis system (GSI) instead of the RUC three-dimensional variational data assimilation (3DVar). As part of the RAP development, modifications have been made to the community ARW model (especially in model physics) and GSI assimilation systems, some based on previous model and assimilation design innovations developed initially with the RUC. Upper-air comparison is included for forecast verification against both rawinsondes and aircraft reports, the latter allowing hourly verification. In general, the RAP produces superior forecasts to those from the RUC, and its skill has continued to increase from 2012 up to RAP version 3 as of 2015. In addition, the RAP can improve on persistence forecasts for the 1–3-h forecast range for surface, upper-air, and ceiling forecasts.

Full access
William P. Kustas
,
Martha C. Anderson
,
Joseph G. Alfieri
,
Kyle Knipper
,
Alfonso Torres-Rua
,
Christopher K. Parry
,
Hector Nieto
,
Nurit Agam
,
William A. White
,
Feng Gao
,
Lynn McKee
,
John H. Prueger
,
Lawrence E. Hipps
,
Sebastian Los
,
Maria Mar Alsina
,
Luis Sanchez
,
Brent Sams
,
Nick Dokoozlian
,
Mac McKee
,
Scott Jones
,
Yun Yang
,
Tiffany G. Wilson
,
Fangni Lei
,
Andrew McElrone
,
Josh L. Heitman
,
Adam M. Howard
,
Kirk Post
,
Forrest Melton
, and
Christopher Hain

Abstract

Particularly in light of California’s recent multiyear drought, there is a critical need for accurate and timely evapotranspiration (ET) and crop stress information to ensure long-term sustainability of high-value crops. Providing this information requires the development of tools applicable across the continuum from subfield scales to improve water management within individual fields up to watershed and regional scales to assess water resources at county and state levels. High-value perennial crops (vineyards and orchards) are major water users, and growers will need better tools to improve water-use efficiency to remain economically viable and sustainable during periods of prolonged drought. To develop these tools, government, university, and industry partners are evaluating a multiscale remote sensing–based modeling system for application over vineyards. During the 2013–17 growing seasons, the Grape Remote Sensing Atmospheric Profile and Evapotranspiration eXperiment (GRAPEX) project has collected micrometeorological and biophysical data within adjacent pinot noir vineyards in the Central Valley of California. Additionally, each year ground, airborne, and satellite remote sensing data were collected during intensive observation periods (IOPs) representing different vine phenological stages. An overview of the measurements and some initial results regarding the impact of vine canopy architecture on modeling ET and plant stress are presented here. Refinements to the ET modeling system based on GRAPEX are being implemented initially at the field scale for validation and then will be integrated into the regional modeling toolkit for large area assessment.

Full access
Molly Baringer
,
Mariana B. Bif
,
Tim Boyer
,
Seth M. Bushinsky
,
Brendan R. Carter
,
Ivona Cetinić
,
Don P. Chambers
,
Lijing Cheng
,
Sanai Chiba
,
Minhan Dai
,
Catia M. Domingues
,
Shenfu Dong
,
Andrea J. Fassbender
,
Richard A. Feely
,
Eleanor Frajka-Williams
,
Bryan A. Franz
,
John Gilson
,
Gustavo Goni
,
Benjamin D. Hamlington
,
Zeng-Zhen Hu
,
Boyin Huang
,
Masayoshi Ishii
,
Svetlana Jevrejeva
,
William E. Johns
,
Gregory C. Johnson
,
Kenneth S. Johnson
,
John Kennedy
,
Marion Kersalé
,
Rachel E. Killick
,
Peter Landschützer
,
Matthias Lankhorst
,
Tong Lee
,
Eric Leuliette
,
Feili Li
,
Eric Lindstrom
,
Ricardo Locarnini
,
Susan Lozier
,
John M. Lyman
,
John J. Marra
,
Christopher S. Meinen
,
Mark A. Merrifield
,
Gary T. Mitchum
,
Ben Moat
,
Didier Monselesan
,
R. Steven Nerem
,
Renellys C. Perez
,
Sarah G. Purkey
,
Darren Rayner
,
James Reagan
,
Nicholas Rome
,
Alejandra Sanchez-Franks
,
Claudia Schmid
,
Joel P. Scott
,
Uwe Send
,
David A. Siegel
,
David A. Smeed
,
Sabrina Speich
,
Paul W. Stackhouse Jr.
,
William Sweet
,
Yuichiro Takeshita
,
Philip R. Thompson
,
Joaquin A. Triñanes
,
Martin Visbeck
,
Denis L. Volkov
,
Rik Wanninkhof
,
Robert A. Weller
,
Toby K. Westberry
,
Matthew J. Widlansky
,
Susan E. Wijffels
,
Anne C. Wilber
,
Lisan Yu
,
Weidong Yu
, and
Huai-Min Zhang
Free access